package com.Lgwd.utils;

import java.util.Random;

/**
 * 随机数
 * @author wade
 * @date 2017年12月6日
 */
public class RandomUtils {
	public static final String ALLCHAR = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNOPQRSTUVWXYZ";
	public static final String LETTERCHAR = "abcdefghijkllmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
	public static final String UPPERCHAR = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	public static final String NUMBERCHAR = "0123456789";
	
	/**
	 * 纯数字指定长度随机数
	 * @param len
	 * @return
	 */
	public static String getRandom(int len){
		String rs="";
		 for(int i=0;i<len;i++)
			 rs+=Math.min(Math.round(Math.random()*10), 9);
		 return rs;
	}
	/**
	 * 带英文字母指定长度随机数
	 * @param len
	 * @return
	 */
	public static String getRandStr(int len){
		String rs="";
		String s ="ABCDEFGHIJKLMNOPQRST0123456789";
		StringBuffer sb = new StringBuffer(); 
		while(sb.length()<len){
			sb=sb.append(s.charAt(len));
		}
		rs=sb.toString();
		return rs;
	}
	
	/**
	 * 返回一个定长的随机纯字母字符串(只包含大写字母)
	 * @param len
	 * @return
	 */
	public static String getRandEng(int length) {
		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for (int i = 0; i < length; i++) {
			sb.append(UPPERCHAR.charAt(random.nextInt(length)));
		}
		return sb.toString();
	}
	
	/**
	 * 指定范围随机数
	 * @param minNum
	 * @param maxNum
	 * @return
	 */
	public static int getRangeStr(int minNum,int maxNum){
		Random rand = new Random();
		int randNum = rand.nextInt(maxNum)+minNum;
		return randNum;
	}
	
	
	/**
	 * 返回一个定长的随机字符串(只包含大小写字母、数字)
	 * @param length 随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateString(int length) {
		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for (int i = 0; i < length; i++) {
			sb.append(ALLCHAR.charAt(random.nextInt(ALLCHAR.length())));
		}
		return sb.toString();
	}

	/**
	 * 返回一个定长的随机纯字母字符串(只包含大小写字母)
	 * @param length随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateMixString(int length) {
		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for (int i = 0; i < length; i++) {
			sb.append(ALLCHAR.charAt(random.nextInt(LETTERCHAR.length())));
		}
		return sb.toString();
	}

	/**
	 * 返回一个定长的随机纯大写字母字符串(只包含大小写字母)
	 * @param length随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateLowerString(int length) {
		return generateMixString(length).toLowerCase();
	}

	/**
	 * 返回一个定长的随机纯小写字母字符串(只包含大小写字母)
	 * @param length随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateUpperString(int length) {
		return generateMixString(length).toUpperCase();
	}

	/**
	 * 生成一个定长的纯0字符串
	 * @param length字符串长度
	 * @return 纯0字符串
	 */
	public static String generateZeroString(int length) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < length; i++) {
			sb.append('0');
		}
		return sb.toString();
	}

	/**
	 * 根据数字生成一个定长的字符串，长度不够前面补0
	 * @param num数字
	 * @param fixdlenth字符串长度
	 * @return 定长的字符串
	 */
	public static String toFixdLengthString(long num, int fixdlenth) {
		StringBuffer sb = new StringBuffer();
		String strNum = String.valueOf(num);
		if (fixdlenth - strNum.length() >= 0) {
			sb.append(generateZeroString(fixdlenth - strNum.length()));
		} else {
			throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth
					+ "的字符串发生异常！");
		}
		sb.append(strNum);
		return sb.toString();
	}

	/**
	 * 每次生成的len位数都不相同
	 * @param param
	 * @return 定长的数字
	 */
	public static int getNotSimple(int[] param, int len) {
		Random rand = new Random();
		for (int i = param.length; i > 1; i--) {
			int index = rand.nextInt(i);
			int tmp = param[index];
			param[index] = param[i - 1];
			param[i - 1] = tmp;
		}
		int result = 0;
		for (int i = 0; i < len; i++) {
			result = result * 10 + param[i];
		}
		return result;
	}
	
	/**
	 * 返回一个定长的随机纯数字字符串(只包含数字)
	 * @param length随机字符串长度
	 * @return 随机字符串
	 */
	public static String generateMixNumber(int length) {
		StringBuffer sb = new StringBuffer();
		Random random = new Random();
		for (int i = 0; i < length; i++) {
			sb.append(NUMBERCHAR.charAt(random.nextInt(NUMBERCHAR.length())));
		}
		return sb.toString();
	}
	
	public static void main(String[] args) {
		System.out.println("返回一个定长的随机字符串(只包含大小写字母、数字):" + generateString(10));
		System.out.println("返回一个定长的随机纯字母字符串(只包含大小写字母):" + generateMixString(10));
		System.out.println("返回一个定长的随机纯大写字母字符串(只包含大小写字母):"
				+ generateLowerString(10));
		System.out.println("返回一个定长的随机纯小写字母字符串(只包含大小写字母):"
				+ generateUpperString(10));
		System.out.println("生成一个定长的纯0字符串:" + generateZeroString(10));
		System.out.println("根据数字生成一个定长的字符串，长度不够前面补0:"
				+ toFixdLengthString(123, 10));
		int[] in = { 1, 2, 3, 4, 5, 6, 7 };
		System.out.println("每次生成的len位数都不相同:" + getNotSimple(in, 3));
	}
}
